In assembling operations for various electric products using electronic components such as IC, soldering is frequently employed in electrical junctions. Recent years, along with progress in automatization of assembling, automatization in soldering operation has also been promoted. However, there remain quite a lot of processes requiring a soldering operation by hand (manual soldering).
Although manual soldering is typically performed using a soldering ion, a tool for manually handling solder includes various devices other than the soldering iron, such as a solder removal device and a hot-air blowing device. The solder removal device is designed to re-melt and remove a solder which has already been soldered. The hot-air blowing device is designed to blow hot air against a solder to melt the solder, and used for both soldering and solder removal. In this specification, they will be collectively referred to as “solder handling device”. Further, an operation of handling solder using a solder handling device will be referred to as “solder handling operation”.
It is desirable that a solder handling operation is performed at an adequate temperature. This adequate temperature depends on a type of solder, a type of solder handling device, a size and a shape of a tip or the like of a solder handling device, or an allowable temperature limit of an electronic component, etc. For example, recent years, solder containing almost or absolutely no lead (lead-free solder) has been regarded as advantageous in view of the global environment, and increasingly used. The lead-free solder has a melting point greater than that of tin-lead eutectic solder by several tens of degrees Celsius, so that an adequate temperature in case of using the lead-free solder becomes greater than that in case of using the tin-lead eutectic solder.
There has been known a solder handling device intended to meet the above need and equipped with a temperature controller operable to adjust a set temperature.
However, if a set temperature based on the temperature controller is in a changeable state at any time, a solder handling operator is likely to perform a solder handling operation at an inadequate set temperature. For example, due to operator's enthusiasm to aim at improvement in operating efficiency, the operator is liable to set a set temperature higher than an adequate temperature. The reason is that, as a set temperature becomes higher, solder is more easily melted to provide more improved operating speed. This usage is undesirable, because it causes a negative effect, such as thermal damage of electronic components.
In order to avoid such an undesirable situation, the temperature controller may have a mechanism for locking a set temperature once it is set (temperature lock mechanism), wherein only a specific person (hereinafter referred to as “set-temperature manager”) is permitted to release the temperature lock (see, for example, the following Patent Document 1).
A system disclosed in the Patent Document 1 comprises a setting card. This setting card has an identification code indicating that an owner of the setting card is a set-temperature manager. Further, a change of a set temperature is permitted only when the setting card is inserted into a card slot provided in a body of a temperature controller and then the identification code is properly authenticated.
Thus, the set-temperature manager can appropriately set a set temperature after inserting the setting card into the card slot, and then lock the set temperature by withdrawing the setting card from the card slot.
The system disclosed in the Patent Document 1 is a digital type configured such that a value of a set temperature is input from a keyboard, and the identification code of the setting card is electrically authenticated.
In addition to the digital type, the input configuration for a set temperature includes an analog type. For example, there has been known one type comprising a variable resistor, wherein a set temperature is changed according to a resistance value of the variable resistor. This variable resistor includes a rotating shaft, wherein the resistance value is changed according to a rotation angle of the rotating shaft. The rotating shaft is coupled to a rotary knob which is adapted to be rotated to allow the rotation angle of the rotating shaft to be changed. The temperature lock mechanism using the setting card as in the Patent Document 1 is unsuitable for such an analog type. Thus, the temperature lock in the analog type has heretofore been performed by physically fixing the knob. For example, there has been known a mechanism in which a locking bolt or a locking nut is tightened using a specialized tool (wrench or driver) to thereby prohibit the rotation of the knob.
However, in such a temperature lock mechanism, a temperature lock/release operation becomes cumbersome and complicated.
[Patent Document 1] JU 2-22144B